To unlock the full rules in the Warhammer 40,000 App, you must purchase a physical copy of the codex and redeem the unique code found in the back.
While many players search for a it is important to note that Games Workshop does not sell standalone digital PDF versions of their codexes. Instead, the modern ecosystem uses a hybrid physical-digital approach: grey knights 40k codex pdf
The original 10th Edition Index: Grey Knights PDF remains available as a legacy reference, though it has been superseded for competitive play by the new codex. Key Features of the 10th Edition Codex To unlock the full rules in the Warhammer
Tactical rules designed for objective control and reactive plays. Core Army Rules grey knights 40k codex pdf